PHYSICAL GEOLOGY. 167 



The salt of Cheshire is partly mined as " rock-salt," and partly- 

 pumped up in tho form of brine. Salt has been produced from brine 

 for more than 1000 years ; for long ages before that there must have 

 been constant waste of the salt going on, especially near the outcrop. 

 This continuous abstraction of salt from below has resulted in serious 

 slips and subsidences of the surface. The earliest recorded sinking 

 took place in 1533 ; since then there have been many others, and the 

 movements are still going on. Northwich is only 20 feet above the 

 sea-level, and the thickness of the salt-deposits is there 180 feet ; 

 "Winsford is 40 feet above the sea, and the thickness of the salt is 

 210 feet. Mr. Dickinson remarks : — '* It is evident from the surface- 

 level being at a considerably less elevation above sea-level than the 

 thickness of rock-salt underneath, the subsidence now so actively begun 

 at Northwich and Winsford may end in the whole of this portion of 

 Cheshire being submerged." AV. T. 



NiLEs, Prof. W. H. On some expansions, movements, and fractures 

 of Rocks observed at Monson, Mass. Proc. Amer. Assoc, vol. 

 xxii. B. pp. 156-163. [See also AVing, p. 171.] 

 Gives an account of phenomena to be observed in some Gneiss- 

 quarries. When a stone of considerable length is quarried from any 

 undisturbed portion of a bed, expansion is found to occur lengthwise in 

 the block, which is slightly longer than the place from which it was 

 broken. This happens only in a IN^. and S. direction. The e:^pansion 

 takes place immediately. Anticlinals are often formed in these quarries, 

 the axes of which are always E. and W. The most common pheno- 

 mena are fractures of the rock, accompanied by explosions and con- 

 siderable displacement. Lateral pressure is the assigned cause of these 

 manifestations. G. A. L. 



NciGGERATH, T. Die Ursachen der Erdbeben. [The cause of earth- 

 quakes.] Das Ausland, pp. 821-824, 851-854, 865-867, 885- 

 888. 

 Perrey, Alexis. Etude du Roseau Pentagonal dans I'ocean Paci- 

 fique. [The Pentagonal system in the Pacific] Compt. Rend, 

 t. Ixxix. pp. 444. 

 Has drawn M. Elie de Beaumont's lines upon the five-sheet chart of 

 the Pacific issued by the French Depot de la Marine, and finds that 

 they coincide to a great extent with orographical and volcanic features. 



G. A. L. 

 PoEY, A. Rapport cntro les taches solaires, les tremblcments do 

 tcrrc aux Antilles et au Mexiquo et les eruptions volcaniques sur 

 tout le globe. [On the relations between sun-spots, earthquakes, 

 and volcanic eruptions.] Compt. Rend. t. Ixxviii. pp. 51-55. 

 Arrives at tho following conclusions : — that atmospheric phenomena 

 and those of the crust of the earth are found generally cumulating 

 towards decennial periods, grouped alike around the maxima and the mi- 

 nima of the spots ; that all the phenomena derived directly or incHrectly 

 from heat correspond more nearly to the minima, while those emanating 



